SanDisk said Monday that it is shipping memory chips that will allow consumers to store more data on tiny Secure Digital flash cards.

The Milpitas, Calif., company’s X4 technology packs four bits of data into each memory cell. To date, flash memory chipmakers typically stored one bit or two bits per cell. Each individual die–or chip–holds 64 gigabits of data, or 8 gigabytes. This is the highest capacity per die in the industry, according to SanDisk.

The technology is shipping now in 8GB and 16GB SDHC (Secure Digital High Capacity) cards as well as 8GB and 16GB Memory Stick PRO Duo cards, the company said.

The memory technology itself–the 4 bits per cell 64-gigabit memory–is codeveloped and co-owned by SanDisk and Toshiba. The X4 controller technology is solely owned by SanDisk.

Flash memory cards sold at retailers are typically not as reliable as solid-state drives–which also use flash chips–sold with laptops. And the higher the density per chip and the more bits per cell, the bigger the challenge for maintaining data reliability. SanDisk says it has met this challenge.

“Our challenge with X4 technology was to not only deliver the lower costs inherent to 4-bits-per-cell but to do so while meeting the reliability and performance requirements of industry standard cards,” Sanjay Mehrotra, SanDisk’s president and chief operating officer, said in a statement.